This invention relates to a method of making a three-dimensional photograph and to the photograph resulting from the method. More particularly, this invention relates to a method of making a three-dimensional photograph, and to a photograph resulting from the method, utilizing at least one rastor to generate the three-dimensional image.
Methods have long been known for generating photographs yielding varying qualities of three-dimensional images. Such three-dimensional photographs differ from traditional two-dimensional photographs in that the three-dimensional photographs yield an image not only having height and width, but also depth. That is, the three-dimensional photograph yields an image appearing to have spacial distances between various components in the image along an axis perpendicular to the plane or surface of the photograph.
One such method of making a three-dimensional photograph utilizes a lenticular screen in order to yield a three-dimensional image. The picture or image information is taken with a line rastor or lenticular screen placed between the film and the subject being photographed, and the position of the film with respect to the subject being photographed is substantially changed between repeated exposures of the film. Thereby, a series of parallel linear images (or "lineations") are printed on a backing layer of what becomes the final three-dimensional photograph.
The backing layer is then mounted on a lenticular screen so that the lineations are aligned with, and parallel to, the lenses on the lenticular screen. If the lineated images on the backing layer are comprised of different camera "views" of a subject taken from appropriately spaced positions of the film, line rastor, and subject, predetermined to provide parallax, the photograph yields an illusion of depth when viewed at appropriate distances from the lenticular screen.
As a practical matter, lenticular screen type three-dimensional photographs suffer from a lack of resolution and clarity because of the nature of the lenticular lens itself. Because it is prohibitively costly to make and use precision cut lenticular lenses, the lenticular screen is typically made out of rolled, cut, or molded plastics. Thus, the screen itself is thus filled with imperfections having a detrimental effect on the quality of the three-dimensional image.
Another problem with lenticular screen type three-dimensional photographs is their severely limited depth-of-field. Because of the inherent limitations of the refractive properties in the lenticular lenses in use and the short focal lengths necessary to produce the precise optics necessary for use of lenticular lenses, only a limited amount of 3-D information can be placed on the film backing in the form of lineations. Thus, the lack of 3-D information translates into a 3-D photograph with a shallow depth-of-field.
Another method of making a 3-D photograph utilizes a rastor not only to lay a series of images on the photograph, but also to view the photograph. Such methods require placing a first rastor in the camera between the unexposed film and lens of the camera, exposing the film with the subject in one position with respect to the film, then moving the subject and film with respect to one another, and re-exposing the film. This sequence is then repeated at least several more times.
The exposed film is then developed and printed or utilized in its developed state to generate the final 3-D image. Because of changes in the dimensions of the film stock during developing, another rastor, having dimensions different from the first rastor, must be used to view the image, or else the image must be enlarged as necessary so the first rastor, or another rastor having dimensions identical to the first rastor, can be used. The rastor is placed over the print or film between the viewer and the film or print to generate the 3-D image for the viewer. If a print is used, frontal lighting of the 3-D photograph yields the 3-D image. If the developed film is used, backlighting of the 3-D photograph yields the 3-D image.
Such rastor type 3-D photographs in the prior art have also suffered from a variety of problems, including lack of clarity and resolution. In the methods of the prior art, the film stocks are dimensionally unstable. Thus, the rastor used to expose the film cannot be used to view the 3-D image unless the developed image is printed on an enlarged film or print stock. Whether a second rastor is used or the image is enlarged, the resulting 3-D image lacks clarity because of inaccuracy introduced by either using a second rastor of different dimensions than the first or by enlarging the print or film to attempt to match the developed image size with the original undeveloped image size. Either method is difficult, time consuming, costly, and a sure source of imperfection in the method, for when the rastor does not match up with the developed film completely correctly, the resulting 3-D image lacks resolution, clarity, and proper illusion of depth.
Another consequence of dimensional instability of the film stock is that wavering moire patterns may result. These patterns will distort the 3-D image with phase shifts that are prohibitively disruptive, especially in large scale applications.
Another problem with methods that utilize rastors to make 3-D photographs has been their failure to maximize diffraction phenomena. Such methods have resulted in relatively poor resolution and clarity by failing to dimension the rastor to concentrate a single fresnel zone on the film during exposure of the film.
Other problems with rastor type 3-D photographs have been caused by the lack of 3-D information placed on the film stock. Because the ratio of rastor periodicity to separation distance (between the film and the rastor) have been low, the number of lineations or separate images placeable on the film without overlap has been fairly low. Moreover, the materials used to separate the film stock and rastor during exposure and viewing have not had the high degree of refraction desirable in order to "compress" more photographic information into a given space on the film stock. This lack of 3-D information results in a narrow depth-of-field.
Another problem with the rastor type methods of the prior art has been the inability of such methods to allow the film to be quickly and easily mounted within, or removed from, the camera for developing. During exposure, the film must be separated from the rastor by a uniform, predetermined distance, but methods of so aligning the film have been cumbersome and inaccurate. One such method holds the film and rastor in position during exposure by means of mechanical clips on a frame holding the rastor and film. The method causes imperfections in the resulting 3-D image, however, because of two sources of error in maintaining uniform separation between the film and rastor during exposure and viewing.
First, the movement of the film and rastor during exposure can introduce movement of film with respect to the rastor. Second, after removing and developing the film, re-mounting for viewing on a mechanical frame and clip apparatus leaves great room for error and non-uniformity of separation. Because uniformity of separation is critical for a quality 3-D image, such sources of nonuniformity greatly degrade the resulting 3-D image.
Other rastor type 3-D methods of the prior art do not move the rastor and film as a unit with respect to the subject being photographed. Instead, they allow both the rastor and subject to move while holding the film stationary. Such methods add another source of error or imperfection because the movements of the rastor with respect to the film must be extremely precise, requiring a cumbersome, precision rastor moving mechanism.
It is therefore an object of the present invention to develop a method of making a 3-D photograph that does not utilize lenticular lenses or any similar lenses, such as certain types of aperture rastors.
It is also an object of the present invention to develop a method of making 3-D photographs utilizing a rastor to expose and view the 3-D image but without requiring either enlargement of the developed image or utilization of a rastor during viewing that has different dimensions than the rastor used during exposure.
Another object of the present invention is to improve the quality of 3-D photographs, especially large scale 3-D photographs. In prior methods the detrimental qualities of moire distortion (wavering phase shifts) and information loss (associated with second or third generation prints made from smaller transparencies) were greatly accentuated, especially on larger scales.
Yet another object of the present invention is to develop a method of making a 3-D photograph that easily and efficiently maintains uniform separation between the rastor and film or print during both exposure of the film and during viewing of the 3-D image.
Another object is to enable the production of first generation images (that is, to enable the film stock used in the first generation to be used in display of the 3-D photograph) in order to obtain optimum resolution, color density, contrast, and realism.
A further object is to develop such a method utilizing a refractive material between the film and rastor or print during exposure of the film and while viewing the 3-D image in order to "compress" more 3-D information into a given space on the film and increase the depth-of-field of the 3-D photograph.
Yet another object is to develop a method of making a 3-D photograph, utilizing a rastor having dimensions that maximize diffraction phenomena by concentrating a single fresnel zone on the film during each exposure of the film.
An additional object is to develop a method of manufacturing a 3-D photograph that can be mass produced in an economical, efficient and quick way.
There are other objects and advantages of the present invention. They will become apparent as the specification proceeds.